Insulated cabinet



1956 L. M. KURTZ 2,729,863

INSULATED CABINET Filed Dec. 11, 1952 2 Sheets-Sheet 1 \nventor: Lowell M. Kur tz,

His A-t'torneg.

Jan. 10, 1956 L. M. KURTZ INSULATED CABINET 2 Sheets-Sheet 2 Filed Dec. 11, 1958 Inventor- Lowell M. Kurtz,

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United States PatentO 2,729,863 INSULATED CABINET Lowell M. Kurtz, Erie, Pa., assignor to General Electric Company, a corporation of New York Application December 11, 1952, Serial No. 325,28 1 Claim. (Cl. 29-45) My invention relates to cabinets, and more particularly to insulated cabinets for use with refrigerators, freezers and the like. a

It has been found that vacuum insulation, for example, of the type described and claimed in the copending application of Herbert M. Strong and Francis P. Bundy, Serial No. 236,788, filed July 14, 1951, and assigned to the General Electric Company, the assignee of the present invention, offers substantial advantages for use in refrigerators, freezers and the like. My invention is an improvement over the invention of the Strong and Bundy application, and, therefore, I do not claim as my invention anything shown or described in said Strong and Bundy application, whichis to be regarded asprior art with respect to the present application. i Because of the greatly improved thermal insulating properties of the insulation of the Strong and Bundy application, a much smaller thickness of such insulation may be employed with the resultant large increase in food storage space for the same outside dimensions of the cabinet. However, these advantages are not achieved without some attendant problems. i i

For example, in conventional refrigerators and freezers with a wall thickness of three inches to four inches there is a substantial space conveniently available for a breaker strip of sufiicient width to insure the desired temperature gradient between the inner and outer wall and to minimize sweating of the outerwall. Similarly, with such wall thicknesses there is ample space available to provide a face surrounding the access opening which is ,of sutlicient width for sealing engagement by a gasket mounted on the door, or, alternatively, of suflicient width for the mounting of a gasket thereon. On the other hand, the efiicient vacuum insulation may require an insulated structure of a thickness of only approximately /2 in. This makes diflicult the provision of a breaker strip of sufiicient width to insure the necessary temperature gradient thereacross. This problem is further aggravated by the fact that, where one or both walls of thesealed evacuated envelope are employed as walls of the refrigerator or freezer cabinet itself, the breaker strip must be made of a material capable of perfect sealing engagement with the walls. of the envelope. In addition, with an actual wall thickness of the order of /2 in., it is exceedingly difficult to provide an adequate surface for either mounting the sealing gasket of the cabinet or for sealing engagement by a gasket.

i Another problem raised by the use of vacuum insulation is that relating to the mounting of various accessories necessary for a complete refrigerator or freezer. .For example, it isnecessary-to provide hinges for swinging movement of the door or lid of the cabinet, and it is further necessary to provide a suitably mounted latch and strike for pressing the lid or door into sealing engagement. In conventional refrigerators themounting of these elements presents no problem since they may be easily mounted by fastening. devicesextending through the walls of the cabinet or door. l-lowever, wherethese walls form a sealed envelope and whereitis necessary to main- 2 tain a very low pressure within the envelope over a prolonged period of time, it is undesirable and relatively impractical to mount hinges, latches, etc., by devices penetrating the walls of the sealed envelope. In accordance with my invention, the above difficulties are overcome and a satisfactorily insulated cabinet employing vacuum insulation is provided.

It is an object of my inventionto provide an improved insulated cabinet. i

It is another object of my invention to provide an improved cabinet construction especially suited for vacuum insulated cabinets.

It is a further object of my invention to provide an insulated cabinet including an improved arrangement for minimizing edge lossesbetween the inner and outer walls thereof. i

It is still another object of my invention to provide an insulated cabinet including an improved breaker strip construction.

It is still a further object of my invention to provide a vacuum insulated cabinet including an improved arrangement for mounting hinges and other accessories thereon. I i

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In carrying out the objects of my invention one of the walls of a sealed evacuated envelope is flanged inwardly generally normal to the remainder of the wall and in a direction extending away from the other wall. A breaker strip composed of a metal of low thermal conductivity is welded to the walls at the flange portion to seal the envelope. The walls include portions extending beyond the breaker strip and a trim strip is secured to these extensions for concealing the breaker strip and providing a finished appearance. Latches,hinges, and the like are mounted on these extensions so that fastening devices extending through the walls formounting such elements do not atfect the sealed envelope, 3 i

For a better understanding of my invention, reference may be had to the accompanying drawings in which Fig. 1 is an elevation view,partly broken away, of'a portion of a refrigerator cabinet illustrating an embodiment of my invention. i

Fig. 2 is a sectional plan view taken along the line 2-2 in Fig. 1 looking in the direction of the arrows.

Fig. 3 is a view similar to Fig, 2 illustrating a modified form of my invention.

Fig. 4 is a view of one form of apparatus formaking' the breaker strip shown in Fig.3. i a i Fig. 5 is a view similar to Fig. 4 showing the parts in a different position. i a

Fig. 6 is an elevation view, partly broken away, of an insulated cabinet showing a modified form of my invention. i

Fig. 7 is an enlarged sectional view of a portion of the cabinet shown in Fig. 6. a a

Referring to Figs. land 2, there is shown an insulated cabinet 1 having a door zjhingedly niounted thereon by means of hinges, one of which is shown at 3. The cabinet 1 includes a metal outer wall4and a metal inner wall or liner 5. The inner wall 5 defines a food storage compartment 6 including a plurality of shelves, one of which is shown at 6a. The space between the inner and outer walls is filledwith a suitable heat -insulating filler material 7, which may be of the type described and claimed in the aforementioned Strong and Bundy application. i r The space between the walls stand 5 is evacuated to provide an insulating structurepf very low, thermal conductivity... Because oi. he. hermal. insulating properties of such structures, as described in the aforementioned Strong and Bundy application, a cabinet approximately Va'inch in thickness of wall construction pro-. ides. insulation comparable to that of conventional refrigs craters where. 3.- to. 4. inohesofiinsulation are employed. In, order to seal the evacuated enyelope provided byv the walls 4 and; 5 a breaker strip. or frame 8 is provided at the forwardportion of the cabinet 1. This breaker strip is preferablymade of a metal of low thermal conductivity in: order to. effect the. perfectsealingengagement with the outer and inner walls required by. vacuum insular tion; for example... stainless. steel has suitable characteristics forthis purpose.

In order that. a sufficiently high temperature. gradient be provided. between the inner and: outer walls at the edge pertion eonnected by the breaker strip, the inner wall: 55is flanged. inwardly; as indicated at generally normal to the main body of the wall 5, and this flange portion 9 extends; in a. direction away from the. outer wall Iuthism nner the end 10 of the. inwardly extending flange portion 9 is spaced a substantial distance from. the ou er wall 4. in. con rast to the relatively close spacing of. he walls 4.- and; 5. throughout the. major portion of their area. As can be seen from Fig. 1, the aforemena tioned flange portion 9 together with the breaker strip or frame 8. formsa picture-frame. construction around the access opening of the food. storage compartment 6. By his construction the breaker strip. 8. is of substantial width nd. th he'material employed, therefor, elfects a sufiicient temperature g adientto insu e that heat leakag from the u r wall to the food storage compartment is minimized and that. the temperature of the. outer wall in he egion f the breaker strip is sufficient to minimize c nden ati n of moisture or swe In the fo m oi invention shown in F g- 2 the o 2 includes, an Qlller wall 1.1 which may be of any conventional materiahsuch as low carbon steel, and an inner wall 12 which is made of a. metal of low thermal conducivity, su h as stainless steel. -.As in he n r i n of he cabinet, he space between the inn r nd uter walls of the door is. fi led with a suitable. fill r m teri l 13, preferably in accordance with the aforementioned Strong and Bundy application. The walls 11 and 12 are s aled adjac nt he r dges in any s i abl n as y el ing as indic ted at; 14, and the sp ce between h llsi e acu ted, W ile, in the form ill t he enti e i n r wall o the do r ha be n f med fr m a single sheet of stainless steel, it will be apparent that a parat breaker strip or frame of stainless s el, si o he rip 8 of the ca in t, could be. emp ye he re.- maining or c ntral por i n of thci ncr ell e n o m for example, of low carbon steel same as the, outer wall 1. Ihe break r st p in ha case w l be we or otherwise sealed to the inner and outer walls of the doo just as he break s r p 8 is w lded. to th nn and outer walls of the cabinet.

A m n i ned pr iously, the cabinet l and th d r ar on e ed by hinges 3- Sims th cabinet and the door are sealed and evacuated and since it is imperative h a ve y low pre sur he maintained v a g p i of time if the excellent properties of the vacuum insulaion a e o be e ai e it is desira le t id av g y mounting de ices penetrate the wa l of the e l d velopes o he cabinet and the door.- In ord r to l mi the p obl m o any h n e mounting d vic s penetrating the sealed envelopes, the outer and inner walls of the cabinet are arranged to include sections extending beyond the breaker strip 8, that is, beyond the end of the .7-. As ereyious y theth slsuess o th walls in vacuum-insulated cabinets is too small to provide a sealing surface of satisfactory width for the gasket. The inwardly extending flange 16 of the extension 15 provides a wider surface satisfactory for sealing engagement by the gasket. Similarly, the outer wall 11 of the door includes an extending section or extension 19 projecting beyond the welded area 14 where the outer and inner walls 11 and 12 are welded or otherwise sealed together. The hinge 3 may then be mounted on the cabinet and the door in any suitable manner, for example, by screws 20 and 21, The screw 20 projects through the extension 15 of the outer wall 4 of the cabinet beyond the breaker strip 8 and, of course, outside the surface of the sealed envelope. Accordingly, the penetration of the wall 4 by the screw 20 to mount the hinge 3 in no way affects the envelope or the vacuum maintained therein. Similarly, screw 21 penetrates. the extension 19 of the wall11 of the door beyond theweld area 14 and therefore be; yond the confines of the sealed envelope of the door. It therefore also has no effect on the envelope or the vacuum maintained therein.

While not shown in the drawing, it will be realized that similar extensions of the walls of the door and cabinet can be employed to provide mounting surfaces for the latch and the strike conventionally employed for holding the door closed and for compressing the gasket into seal: ing engagement with the corresponding face of the cabinet.

In order to conceal the various welds and toproyide a pleasing finished appearance at the front of the cabinet a trim strip 22, which. maybe of conventional plastic material, is employed. l One end of the trim. strip 22 is received within recesses provided by a return bent portion 23 of the extention 15 and a plurality of clips 24. The clips 24 have one leg thereof received within the return bent'portion 23. The other edge of the trim strip is s cu d to the e ensio .8 oi e inne Wall. 5 b any suitable fastening device, such as screws 25, passing thr u h the r aker st ip. and he extension 13-. .A in h c o h e s emp o ed fo mount n the hinges 3'. th re s 25 pe e a e the inner W l 5 be ond the b e st ip 8 and e ond t e eale en e p so t at h y ikewise have n e fect on the a ed envelo e o t e cabinet or th uum o be mai ained the nrim s p is i i rl Pr ided or m r n a n she appearance to the marginal edge of the door; One edge of e im strip 26 is o n ct d b sc s ne o ish, i shown at 2 7, to the extension 19 of the outer wall 11. The provision of the extension 19 beyond the edge 14 of the sealed envelope of the door permits the use of fasteners, such as th c ws '27; h ch p n t at h o te l 1. withou any dense o a f c ing he acu ma n ined within t aled en e o the d or- In d ti he sc ew a mnl d r'm umi h gasket h r b P idi a mo ti n men o the gasket without effect orithe vacuum maintainedwithin .the'sealed envelope. The other edge of the trim strip 6 s u d sc e s one of w i h is s own at 2. to a ra et o st i .2 which is ed a 0 to the nne wall 12 of the door. a

n the t rn; lu rat in ie,- 1 sepa ate t imstrins 22 are p ovid a st sid s p and bo om of the cabine n order to P ov e. a fini he PP3I3P9 a co ne s a separa e c rner ie eafit s tir' yi edat sash .ot t corner a eac rn Piece is r an to over.- lap h ends o cour e. he ve ti l and ho iz nt l m s ip A ernativ l a sin trim stri m ld d a 9 pi 'ce trams cou d. be emp o ed in l eu o t e orizon a and ertical rim s r s and co ne ieces- :11; orde to d ce ai c r ulation and h nce tha ansfe b s nect i the P 99 'betw M T. t ip trips a sui able hea -insulat n ma erial such glass are, may be dis osed ween th breake st i 8 an he str p .ZZ ar r. s mil rl betw en. h inner wall '12 of the door and the trim strip 26.

In Fig. 3, there is shown a modified form of my invention which differs from tha tjust described in; the nature of the breaker strip employed for the cabinet and in the nature of the marginal edge or" the inner wall of the door. The same numerals have been I employed to designate corresponding parts in Figs. 2 and 3. i In order to minimize the heat transfer between the inner and outer walls of the sealed envelope at the edges thereof, that is, through the breaker strip, it is desirable that this breaker strip be made as thin aspossible, thereby increasing its resistance to heat flow therethrough. On the other hand, it is essential to the maintenance of a vacuum within the sealed envelope that a perfect Weld be secured between the breaker strip and the inner and outer walls. If the breaker strip is made too thin, there is danger thatdefective welds may be secured, a minimum thickness of metal being necessary to insure a perfect weld throughout the length of the weld area, particularly under mass production manufacturing conditions. In accordance with the form of invention shown in Fig. 3, a minimum heat conductivity through the breaker strip is secured while still maintaining the conditions desirable for insuring a perfect weld. Thus, the breaker strip 31 is provided with longitudinal edge portions 32 and 33 which are of sufficient thickness to provide the necessary material for satisfactory welding. By way of example, these edge portions may be at least .018 inch thick, this being considered a minimum thickness for insuring a perfect weld throughout, under manufacturing conditions. The portion of the breaker strip intermediate these edges 32 and 33 is corrugated to provide a substantially longer heat flow path than is possible with the straight or fiat breaker strip 8 employed in the form of invention illustrated in Fig. 2. In addition to the increased resistance to heat flow provided by longer heat flow path through the corrugations the thickness of the breaker strip in the central region between the edges 32 and 33 is substantially reduced over that existing at these edges. 'Thus, the resistance to heat flow is increased both by increasing the length of path through which the heat must flow and also by substantially reducing the cross-sectional area of the material through which the heat must flow.

Similarly, the marginal portion of the inner wall 35 of the door inwardly from the edge 36 thereof is corrugated, as indicated at 37. As in the case of the breaker strip 31 it provides an edge 36 which is of sufficient thickness to provide satisfactory welding and a corrugated portion 37 of substantially reduced thickness. As was mentioned in connection with Fig. 2, it will be apparent that the portion 37 could be formed, like the breaker strip 31, as a breaker strip separate from the central portion of the inner wall 35 of the door, having edges of sufi'icient thicknessfor welding to the outer and inner walls of the door and an intermediate central region of corrugated construction and of reduced thickness.

In Figs. 4 and 5 there is illustrated diagrammatically one arrangement for making the breaker strip 31. As there shown, the breaker strip 31 is firmly gripped at its longitudinal edges 32 and 33 between a lower die 38 and an upper clamping member 39. The die 38 and the clamping member 39 may be held in firmly gripping engagement with the breaker strip 31 in any conventional manner well known in the art for gripping the edges of sheet metal structures. The lower die is formed to include a plurality of depressions or corrugations 40 into which the breaker strip 31 is adapted to be forced in forming it into the ultimate corrugated shape. In order to effect movement of the breaker strip into the depressions 40 and the lower die 33, an upper die 41 is provided. This upper die includes a steel backing member 42 and a face 43 formed of some deformable material such as rubber.

After the breaker strip 31 has been assembled and clamped in the position shown in Fig. 4, a downward force is exerted against the upper die 41 moving it to the position shown in Fig. 5. During this downward movement the die 41 forces the breaker strip 31 into conformity withthe depressions 40 of the lower die 38, thereby forming the central portion of the breaker strip intermediate the edges 32 and 33 into the corrugated form shown. The deformable face 43 of the upper die assumes the shape of the corresponding face of the lower die, as shown in Fig. 5, to urge the bneaker strip effectively into the depressions 40 of the lower die. In press ing the breaker strip into these depressions, it can be seen that the material of the breaker strip is necessarily drawn or lengthened to provide a thinner cross section in this intermediate area and, as mentioned previously, providing a greater length and, hence, greaterfiow path between the edges 32 and 33.

Another modified form of my invention is shown in Figs. 6 and 7. For convenience in positioning on the drawing, the freezer illustrated in Fig. 6 has been shown as of the chest type with a topopening lid 44. However, it will be realized that this figure equally well illustrates an upright type freezer merely by shifting the position so that the righthand edge becomes the bottom of the cabinet. In the form of invention shown in Figs. 6 and 7 a sealed envelope 45 is provided, including two walls 46 and 47. The inner wall 46 forms the liner defining the storage compartment 48 of thefreezer. The cabinet includes a separate outer wall 49 and the envelope 45 is adapted to be received within the outer wall 49 from the bottom of the freezer. After assembling the envelope within the outer wall of the cabinet, .a separate sheet forming the bottom of the cabinet is secured in any suitable manner to the outer wall 49 to complete the cabinet I i In the form shown in Figs. 6and 7 the pictureframe construction previously described is not employed and the portion of the cabinet framing the access opening projects inwardly a much shorter distance than in the form previously described. In the form shown in Fig. 7 the door 44 differs fromthat previously described and includes an inwardly projecting portion .50 providing a long, narrow 'gap 51 between the door and the cabinet to minimize heat leakage. I e i a p The walls 46 and 47 are connected by a breaker strip 52, which, as in the forms previously described, maybe of a metal of low thermal conductivity such as stainless steel. It may furtherbe corrugated as in the form shown in Fig. 3. The breaker strip 52 is welded to the .inner wall 46 at 53 and to the wall 47 at 54. .As in the form previously described, aheat-insulating filler material .55 is provided within the envelope 45. The structure thus far described is mounted on the forward edge of the outer wall 49 by suitable fastening means such as screws, one of which is shown at 56, extending through the breaker strip and the wall 47 beyond the weld area 54. Hence, the screws 56 penetrating the breaker strip and the wall 47 have no effect on the vacuum maintained within the envelope 45. In order to effect mounting by the screws 56 a bracket 57 is welded or otherwise secured to an inwardly extending flange 58 of the outer wall 49. The screws 56 are adapted to engage a downwardly extending leg 59 of the bracket 57. A sealing gasket 60, which may be of rubber or similar compressible material, is included adjacent the bracket 57.

Since, as mentioned previously, vacuum insulated walls are quite thin, sufiicient insulation being provided by a wall of, say, /2 inch thickness, the flanged portion 58 extends inwardly beyond the bracket 57 and beyond the plane of the liner formed by the major portion of the inner wall 46. This provides an extending section or extension of sufficient width to provide a face for the gasket 61 employed for sealing the food storage compartment 48. In order to conceal the screws and welded surfaces and to provide a finished appearance at the front edge of the cabinet, a trim strip 62 is employed. The extension 58 also serves for mounting one edge of the trim strip 62. For this purpose the extension 58 includes a depending flange 63 and the upper edge of the 7 trim strip 62 is secured to the depending flange 63 by suitable fastening devices, foneitarnfilefscrews; *ene q f which is shownfatbd, The screws6'4l are, as shown, also etfe ctive- -for mc'iunting' thygask'et 61 in position, clamping a tail 65,21: the gasket between the 'trim strip "and the flange order to provide a mou nffor the lower edg e' of the breaker strip 62 the inner wall 46 is flanged iriwardly as indicatedat 66 and then upwardly as indicated at 67, The lo wer edge the trim strip 62 is secured to the upwardly extending flange in "any suitable manner, as by screws, one of whi chis shown at 68 i K As the form previously described, these extensions 51? and 66 ofthewalls which project beyond thefs'ealed envelope provide formqnnting"the trim strip by screws or other simple fastening nevimma penetrate these extensions wrth out ha'ving any efiecton the sealed en .l p r t... .1 .1 The ado; or lid 44 inclndes an outer wall 69 and an inner wall 70;- The inner ivall 7 tlincludes a downwardly extending" narginal'fiang ed portion 71which corresponds generally'to theinfwar'dlyextending marginal flange 9: in the cabinet'constructionshown inFig. 2; The walls 69 and 70 are joined by breaker strip 72 for sealing the envelope formed by the walls 69 and 79. As in the forms previously described, this breaker strip; is" preferably formed of a metal o f'lo w' heat conductivity such as stainless steel. It may further be corrugated as in the form shown in Fig. 35 In the form illustrated in Fig. 7 one edge of the breaker strip is welded directly to the flange 71, inner wall 70, as indicated at 73, and the other edge is welded to a'brack et 74 which in tiirn is welded to the outer wall 69 as indicated at 75. It will be apparent, however, that the breaker "strip 72' could be formed with a flanged portion, similar to the breakerstrip 8 in Fig'. 2, which'eould be welded directly tothe onte r wall 69 thereby permitting the omission of the bracket 74'. In order to provide a supporting'su'rface 'for"hinges, latches, etc., the outer wall 69 includes an extendingp'ortionor extension 76 which extends beyond the weld region 75 and beyondfthesealed envelope bounded by the breaker strip extension 76- includes a downwardly extehdi g edge 77 and'inwardly extending section'78 for engagement by the gasket 62'an'd resen 'downwardly extending section 79. Therelatiyely wide face 7 8"prbvides adequate surface for engagement by'the sealing asket 61'. In order to provide finished apparance'for "the door a trim strip 8tl'is employed The" loweredge 81 of this trim strip is formed of generally UQshapedcrOSssection so as to overlapthe end 82 of the inwardly extending flanjg'e 71 of the inner wall "and the weld area'at 73 where the breaker strip 72 is joined to this flange 71. The neumi ger trim strip 80is"co'mi 'le'te d by'any suitable fastening devices, for example, by screws, one of vflv'liibfi'ifsne "af'ss; which enetrate the'tri'rnstr'ip' so an thedownwardlyextfid' gsection'j'or flange 79 of the oiitervwall'6 9." the'i: ns truction shown, the breaker strip 'is"efiectivelyrndiinted by screws or other siinple fastening devices which actually penetrate the outer wall without having any" etfect onthe'sealed envelope forming the inajorportion the Altho'ngh not shown in this figure, "it'will be apparen that the extension 76 of the tifiili hvfilll 62 of the door and the outer wall 49 of the cabinet provide portions enteriding'beyond the sealed envelope in each case for the, mounting of hinges, latches, strikes," etc. without any danger tli'a'tthe fastening devices elements willpenetrate the vacinrn ins illat'ed' scale ropes;

' WhileI h nd described specific embodiments of my. invent on, I ,0 not desire that my invention be limited to the particiilar constructions shown and described, andjI intendby theappended'claim to cover all modifications within he spirit a d scope of my invention.

' What I na e newan d des re to secure by Letters Patent of'the United States is: U i 1 Ah inslilating stricture including a sealed evacuated envelope co is inga fir'st wall, a s'econdwall, said'second wall incl g 'a flange pbrtiodektending generally lbrmal lt o m an ofrsja'iizi seabird all in a direction awaffronisaidfirst wane breaker strip of a material lowthe rnialcenductivity disposed in a direction'geii erallynqrrna l to walls andse alingly engaging said w l s t sam lers, ai'i ss ssi n'i ope s first l ncludin a secti n t endin bsy nd s d breaker n a til i i ia ha one d e ssi t fl t d extending ection o s i fi s Wall and Qispq e s y P a el to said breaker strip, the other edge of said trim strip being formed in Itkshaped cross section, the end of "said flange portion of said second wall being received within said tJ shaped cross section of said breaker strip, and a fastener penetrating said extending section of said first Wall for mounting said trim strip.

References Cited in the file of this patent S'l ATES PATENTS 1 6 ,258, D w ey u 6, 1 28 '1',8 45;3'53 sn I L- Feb. 16,1932 2,000,882 con er" May7, 1935 2,038,763 spheuen Apr. 28, 1936 2,034,201; Knight June 15, 1937 2164143 Miirite'rs June 27,1939 2,166,629 White July 18,1939 2,256,013 Bronse Q.-- Sept. 16, 1941 23 71,937 ,Gdiilooze Mar; 20, 1945 -+V-,-- 1950 

